CHICAGO, AUG. 31 -- Federal authorities today struck what they hope will be a fatal blow to this city's largest and most ruthless street gang. After a federal grand jury returned indictments against 39 people Wednesday, more than 250 federal, state, and local law enforcement officials moved in on gang leaders this morning in a predawn raid named "Operation Headache. By mid-afternoon, 22 allegedly high-ranking members of the "Gangster Disciples," which boasts a membership of thousands, were in custody. Law enforcement officials said they expect to arrest the remaining defendants within a week, including Sonia Irwin, a Chicago police officer who is rumored to have been living with Gregory Shell, the gang's second in command. "We have taken off the top echelon, and we have bitten off the head of the snake," James Burns, U.S. attorney for the Northern District of Illinois, told a press conference. "This has been happening for 25 years, and we needed to attack at the top. This organization is going to be significantly crippled now. The indictments charge gang leaders with conspiracy to distribute cocaine, crack, heroin and marijuana as well as 45 other counts, including violation of gun control laws and extortion. The gang